AIR install problems

I have problems with AIR and cannot go forwards or backwards.

I am running in Windows 7.

According to Windows "Programs and Features" I have AIR 17.0.0.144. But when I try to Uninstall from there, I get

"This program requires a version of Adobe AIR which cannot be found. Please download the latest version of the runtime from http://www.adobe.com/go/getair, or contact the application author for an updated version."

When I download and run the installer for 17.0.0.172, the GUI states that the install has been successful. But it hasn't, and the log contains:

[2015-05-30:15:49:31] Runtime Installer begin with version 17.0.0.172 on Windows 7 x86

[2015-05-30:15:49:31] Commandline is:

[2015-05-30:15:49:31] No installed runtime detected

[2015-05-30:15:49:34] Relaunching with elevation

[2015-05-30:15:49:34] Launching subprocess with commandline c:\users\cem\appdata\local\temp\airef2f.tmp\adobe air installer.exe -ei

[2015-05-30:15:49:35] Runtime Installer begin with version 17.0.0.172 on Windows 7 x86

[2015-05-30:15:49:35] Commandline is: -stdio \\.\pipe\AIR_7084_0 -ei

[2015-05-30:15:49:35] No installed runtime detected

[2015-05-30:15:49:35] Starting silent runtime install. Installing runtime version 17.0.0.172

[2015-05-30:15:49:36] Reinstalling c:\users\cem\appdata\local\temp\airef2f.tmp\setup.msi

[2015-05-30:15:49:37] Runtime Installer end with exit code 0

[2015-05-30:15:49:37] Elevated install completed

[2015-05-30:15:49:39] Got an unexpected fatal error while quitting: [ErrorEvent type="error" bubbles=false cancelable=false eventPhase=2 text="Unhandled exception TypeError: Error #1009" errorID=1009]

[2015-05-30:15:49:39] Runtime Installer end with exit code 5

When I try to run an AIR application, I get the same message above about a version of Adobe AIR which cannot be found.

The problem survives reboots.

Is it possible to recommend how I can get out of this state?